(CNN) -- Bolivia President Evo Morales declared a U.S. diplomat "undesirable" Monday amid allegations that the United States asked a visiting scholar and Peace Corps volunteers to keep tabs on Cubans and Venezuelans in Bolivia.

Morales said a security assistant for the U.S. Embassy -- identified by the Bolivian Information Agency as Vincent Cooper -- violated the rights of Bolivian citizens and offended the country, the news agency reported Monday.

U.S. officials admitted that someone at the embassy made an inappropriate suggestion, the information agency reported, but the U.S. ambassador to Bolivia, Philip S. Goldberg, denied Monday that the embassy asked anyone to spy.

"I respect the sovereignty and dignity of Bolivia, and I am ready to talk with Bolivian government representatives to clarify everything and present all the facts," the Bolivian Information Agency quoted the ambassador as saying.

"My immediate thought was 'Oh my God. Somebody from the U.S. Embassy just asked me to basically spy," he said. "I was in shock that something like that would happen to me -- just a humble Fulbright scholar who's here to do research."

In Washington, Sean McCormack, a spokesman for the U.S. State Department, told reporters Monday that U.S. embassies are under instructions not to ask Fulbright scholars or Peace Corps volunteers to act "in any way, shape or form" on behalf of the U.S. government as intelligence agents.

The controversy erupted after van Schaick said Cooper asked him in a November meeting at the U.S. Embassy in La Paz to report the names and addresses of Cuban and Venezuelans working in Bolivia, according to the Bolivian Information Agency.

"I smiled and just sat there because I did not want to show that it completely dismayed me to be asked such a thing," van Schaick said, according to the news agency.

The U.S. Embassy in Bolivia said in a statement Monday that Peace Corps volunteers had been mistakenly given a security briefing in July meant for embassy staff asking them to report "suspicious activities," The Associated Press reported, though Goldman said "nobody at the embassy has ever asked American citizens to participate in intelligence activities here."

It was unclear Monday whether the Bolivian government would seek the expulsion of any U.S. Embassy employees in light of the president's declaration of Cooper as an "undesirable" person.E-mail to a friend